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InfluxDB
Power Real-Time Data Analytics at Scale. Get real-time insights from all types of time series data with InfluxDB. Ingest, query, and analyze billions of data points in real-time with unbounded cardinality.
I'm not using it (I self-host Firefly III) but it looks like a lot of other people do use it (based on the number of GitHub stars and Google Play reviews) and that it's maintained (based on the past month's activity on GitHub).
NOTE:
The number of mentions on this list indicates mentions on common posts plus user suggested alternatives.
Hence, a higher number means a more popular project.